1. Field of the Invention
The present invention relates to a mechanized tent. In particular, it relates to a mechanized tent having a frame and a collectable tarp attached to the frame which can be raised and lowered over pallets of produce or the like, particularly useful for fumigation of produce, e.g. imported products. Furthermore, it relates to those tents, which have a plural crew system for elevating and lowering the tarp, as well as including a composite closing structure for sealing the tarp to a floor.
2. Information Disclosure Statement
Once fumigated, produce has a shelf life of at most ten days to two weeks. It is therefore desirable to fumigate the produce close to the place where it will be ultimately sold. For imported produce, this place is typically inside a dock building or warehouse located at a port of entry. Pallets of the produce are unloaded from a ship and placed or staged on the floor of the dock building.
Known methods of fumigating produce involve covering the pallets of produce with a polyethylene or plastic impregnated tarpaulin and then introducing a gas, e.g., methyl bromide, or other gas(+) atmosphere under the tarp to kill live insect infestations. Workers climb on top of the pallets or use poles to pull the tarp over a group of pallets. Because it is necessary for the gas to circulate freely on all sides and the top of the pallets, the tarp cannot lay directly on the top of the pallets. The United States Department of Agriculture requires that a space of about two feet be provided on the top of the pallets, and at least two feet on their sides to allow room for the placement of fans to facilitate the circulation of the fumigation gas. The fans may be tied down with rope to prevent them from moving. Several hoses for introducing the gas is secured to the top of selected fans. The volume of space under the tarp, i.e., the total cubic feet, determines how many fans and points of introduction are required.
One method for maintaining the required space on the top of the pallets is to erect wood frames in the shape of a xe2x80x9cTxe2x80x9d or an xe2x80x9cAxe2x80x9d at each corner and attach rope between each xe2x80x9cTxe2x80x9d or an xe2x80x9cAxe2x80x9d to create a web of support for the tarp. The side space is maintained by draping the tarp outward as it contacts the floor of the dock building and securing it in that position by placing flexible vinyl tubes (approximately 6xe2x80x3 in diameter and 4xe2x80x2 long) filled with sand on top of the edge of the tarp. At least 2 feet of excess tarp remains beyond the sand tubes.
The steps involved in pulling the tarp over the pallets, setting up the fans, attaching the introduction hoses to the fans, handling hundreds of tubes of sand, and dismantling and storing all of the above equipment, and repeating the process upon completion, require many labor intensive hours.
Improvements to the conventional method of fumigating produce include permanently suspending the tarpaulin from an overhead frame and lowering the frame over the pallets as needed. Such a frame may be made from welded trusses to form a disassemble one piece unit of varying dimensions. The typical frame size may be 50 feet long by 250 feet wide, but may be larger or smaller depending upon the spacing between support columns in the dock building. To the underside of the frame a tarpaulin is attached which has been manufactured with grommets, i.e., tabs and eyelets, specific to the frame it hangs from.
The frame may be raised and lowered by a system of cables and pulleys located above the unit which are attached to exposed barjoists on the underside of the roof of the dock building. The cables are connected to hand-operated or motor-operated winces mounted on the support columns in the dock building. Workers simultaneously crank the winches to lower or raise the frame to a height above the pallets that allows the required 2 feet of space between the tarp and pallets of produce.
A typical tent can be lifted by twelve or more active pickup points. Between each of these points two counterweight sandbags are deployed to offset the self-weight of the frame and the polyethylene enclosure. Each truss section of the frame spans approximately fifty feet with two mid-point sandbags. These tend to become hung up from friction and pull at an angle to prevent the sandbag from lowering onto the polyethylene enclosure as it is elevated.
A difficult and time-consuming job associated with operating such a system is gathering up the tarp, which overhangs from the sides of the frame before the frame is raised. This is necessary because the typical dock building height of about twenty-two feet is limited to about eighteen feet by overhead piping, electrical conduits, etc. When the support frame is raised to the maximum height permitted by these obstructions the tarp hangs down low enough to catch the tops of forklift trucks as they move the pallets of produce in and out of the tent area.
One known way of gathering up the tarp on the sides is to run horizontal plastic pipes through double-thickness portions of the tent walls, which form pockets. These pockets can be located at approximately one-third and two-thirds of the wall height and are tied up to the top framing with rope every ten feet or so. Pulled ropes raise the pockets and thus gather the sides of the tent. This method is also time-consuming, however, because it requires numerous tie-up procedures in order to completely raise the tent, e.g., usually at ten to twenty foot intervals around the tent perimeter.
U.S. Pat. No. 645,890 to Conrad discloses a tree-protector having a suitable mast or pole, and a bracket with two supporting arms connected with the pole one arm above another arm. There is also a pulley or sheave in the extremity of each of the arms, and a collapsible or foldable tent. A plurality of distending hoops are attached to the tent and a halyard is connected to the top of the tent and leads around the sheave in extremity of the lower arm of the bracket for bodily raising and lowering the tent and for holding it in an elevated position. Elevating cords are attached to the lower hoop and a second halyard extends over the sheave in the upper arm of the bracket for independently raising and lowering the lower end of the tent.
U.S. Pat. No. 4,033,367 to Johnston describes and illustrates a tent fumigation apparatus for placement over a building to allow fumigation of a building by introducing fumigation into the tent. The preferred tent includes pie-shaped sections, at least some of which have ties allowing sections to be tied off for reducing the size of the tent and conforming it to the shape of the building. Tube means is provided to be affixed to the bottom of the tent for sealing purposes. The tent may include a lifting structure a the top and a cover for closing an opening at the lifting structure. At least one slot is provided in the tent for entrance and egress.
U.S. Pat. No. 4,229,914 to Lucas provides a readily erectable and/or demountable building structure comprising a plurality of arch frames in vertical planes extending transversely of and spaced apart longitudinally of the building structure. Each frame has a retainer means for retaining the longitudinal beaded edges of flexible strip roofing material. The retainer means are of groove-like or channel-like form to receive the longitudinal beaded edges slidingly therein. Preferably two strips are provided between each pair of neighboring arch frames such that when in position they each extend across the space between the two arch frames of each pair with the strip""s width and length dimensions directed respectively longitudinally and transversely of the building structure (and such that a gap is provided between the adjacent strip ends in the structure""s roof), the strips being tensioned in the direction of their length dimension, i.e. transversely of the building structure). Preferably each strip has a shape in its unstressed state such that when tensioned in the direction of its length dimension, it adopts a configuration that is concave to the exterior of the building structure.
U.S. Pat. No. 5,641,463 utilizes many of the aforementioned improved technique features and additionally incorporates unique features, which are more fully discussed in conjunction with some of the drawings described below.
U.S. Pat. No. 5,918,614 to Lynch defines and illustrates a canopy structure, kit and method, which permits a user to custom configure a canopy shelter in almost unlimited curvilinear shapes. To accomplish this, a flexible sheet that is elastic in at least one, but preferably two dimensions may be secured over an area to be sheltered. Anchors connect the sheet either directly to the surface, such as the ground, or to an object, such as a tree or building, secured to the surface. A support pole is interposed between the surface and the sheet; and this support pole is sufficiently long to deform the sheet in the direction(s) of elasticity and thus exert a compression force on the pole. A plurality of support poles of varying lengths may be formed from identical pole selections, and base plates and dome elements may be used on the poles. The anchors are formed to engage the central portion of the sheet so that even greater design flexibility is possible. The sheet is preferably spandex and may be coated with protective materials, and it may be printed with a desired pattern.
U.S. Pat. No. 5,964,236 to Berke discloses a method and apparatus for covering cargo. The cargo is covered by use of a tarp and a frame that extends over the tarp. A number of cords are connected to the tarp and a plurality of couplers interconnect the cords to the frame. The couplers releasably connect the tarp to the frame so that the tarp can be dropped onto the cargo once the frame is moved into a position over the cargo, for example, a forklift. Preferably, the cords include free terminal end sections that can be pulled from ground level to disconnect the cords from the frame when desired, so that walking across the cargo can be avoided.
U.S. Pat. No. 5,974,740 to Park describes and illustrates an adjustable tarpaulin that can be adjusted to various predetermined lengths, and more securely fastened. The adjustability of the adjustable tarpaulin is provided by having one or more sets of valances of the top layer and valances of the bottom layer. Because the valances are free on one end, the length of each of the valance side edges may be adjusted as desired and the valances provide two different pull angles to share the load of the tarpaulin. By doing so, the adjustable tarpaulin enables the tarpaulin to be adjusted between two or more prefixed sizes. Moreover, the adjustable tarpaulin can provide the distribution of the load from more than one angle so stress and the load will be distributed over two different sets of tie points.
U.S. Pat. No. 6,422,253 to the same inventors herein provides a mechanized fumigation tent with a composite closing structure. The composite closing structure is connected to the bottom perimeter of side curtains for sealing the bottom perimeter of the side curtains. The composite closing structure has at least a first component and second component. The first component is a structural support component and has sufficient rigidity to flex no greater than 6 inches over a 10-foot length with a fulcrum weight of 100 pounds. The second component is a sealing component and is formed of flexible material. Further, the sealing component may be a flexible base mounted along the bottom perimeter for receiving, holding and releasing water from an external water supply. When the sealing component holds water, it will seal the tent to a floor. In a preferred embodiment, the structural support component is formed of a triangular cross-sectional shape. The structural support component may be embedded within the sealing component or connected to an outside of the sealing component.
U.S. Pat. No. 6,450,188 to the same inventors herein provides a mechanized fumigation tent, which includes a frame suspended from a structure by support cables, the frame having an underside; a tarp adapted to be mounted to the top side of the frame. The tarp hangs from the frame and defines a tent having a top and side curtains that have a lower periphery defining a bottom perimeter. There is also a sealing arrangement for connecting and sealing the top of the tarp to the frame; a first plurality of cables for raising and lowering the side curtains and being connected to the side curtains and to mechanism for raising and lowering the first plurality of cables; and a second plurality of cables for raising and lowering the frame and being connected to the frame and to mechanism for raising and lowering the second plurality of cables.
Not withstanding the above prior art, there is no teaching which anticipates or renders the present invention obvious. Thus, it is neither taught nor suggested to use a system with a ceiling-mounted suspended frame with a fumigation tarp position atop the support frame in a sealed fashion. Likewise, the prior art is deficient in teachings related to cooperating clews or other present invention features, as more fully developed below.
It is an object of the present invention to provide a large mechanized fumigation tent which incorporates the height of the supporting frame within the tarp structure to eliminate the extra space otherwise needed when the support structure is stacked above the gathered, stored tarp.
It is another object of the present invention to decrease the total weight needed for an efficiently operated fumigation tent.
It is also an object of the present invention to provide a fumigation tent, which does not require any water or sandbags to seal tarp side curtains onto the floor. There is a composite closing structure which includes a structural support component and sealing component that seals the side curtains to the floor.
It is yet another object of the present invention to provide a large fumigation tent for fumigating produce, logs, textiles, wood products, and other forms of potentially infested imports which can be quickly, conveniently and freely raised and lowered over pallets of the produce.
It is also an object of the present invention to provide a fumigation tent that does not interfere with the operation of forklift trucks as they move pallets of the produce in and out of a tent area and that does not require extensive curtain tie-up procedures to accomplish this.
Another object of the present invention is to provide a fumigation tent which can be raised from a single remote location so that personnel need not be near the tent area after fumigation is complete since exposure to residual gas, which may not have been evacuated from some pallet areas, is possible and can be harmful.
It is yet another object of the present invention to provide for alternative mechanisms for first lifting side curtains of the tarp and lowering the entire structure and then the side curtains of the tarp.
A further object of the present invention to provide a system which seals the tent to the floor of the dock building and which can be easily raised with tent or independently of the tent.
The present invention provides a fumigation tent which includes a frame suspended from a structure by support cables, the frame having an underside; a tarp adapted to be mounted to the top side of the frame, the tarp hanging from the frame defining a tent having a top and side curtains having a lower periphery that defines a bottom perimeter; means for connecting and sealing the top of the tarp to the frame; a first plurality of cables for raising and lowering the side curtains and being connected to the side curtains and to means for raising and lowering the first plurality of cables; a second plurality of cables for raising and lowering the frame and being connected to the frame and to means for raising and lowering the second plurality of cables.
The present invention also provides a composite closing structure connected to the bottom perimeter of side curtains for sealing the bottom perimeter of the side curtains. The composite closing structure has at least a first component and second component. The first component is a structural support component and has sufficient rigidity to flex no greater than 6 inches over a 10-foot length with a fulcrum weight of 100 pounds. The second component is a sealing component and is formed of elastomeric flexible material.
The sealing component may be flexible hosing, flexible synthetic foam, or flexible rubber. Further, the sealing component may be a flexible base mounted along the bottom perimeter for sealing the structural support component in place. When the sealing component holds the structural support component in place, it will seal the tent to a floor.
In preferred embodiment, the structural support component is formed of triangular or tubular cross-sectional shapes. In addition, the structural support component may be elongated metal sections, elongated wood sections, elongated plastic sections, and the like. The structural support component may be within the sealing component or outside the sealing component.
The present invention further provides for attachment of winch cables to a first suspension means and a second suspension means, which in turn are attached to the winches by winch chains. There is at least one master suspension means for harmonizing the movement of the first plurality of cables and at least one curtain suspension means for harmonizing the movement of the second plurality of cables. Preferably, the winches are motorized and can be operated by remote control. In addition, in a preferred embodiment, first suspension means and second suspension means are clews. (This provides an important safety advantage, because personnel do not have to be near the tent while it is being raised. Therefore, personnel can avoid being exposed to any lingering fumigation gas which is hazardous.) It is also preferable that hand winches with cables be located near the motorized winches, so that they can be attached to the clew plates to provide emergency back up in case electrical problems occur.
Other advantages and characteristics of the present invention will become apparent in view of the description and accompanying drawings that follow.